THE INFLUENCE OF THERMAL PERFORMANCE OF TWT CATHODE-HEATER ASSEMBLY BY DIFFERENT CONTACT FORM BETWEEN INNER HEAT SHIELD AND SUPPORT CYLINDER

In this paper,the influence of thermal performance of cathode-heater assembly of Traveling Wave Tube(TWT),which has different contact form between inner heat shield and supporting cylinder,is analyzed using the simulation software ANSYS.With both thermal radiation and heat conduction are considered,the temperature and heat flux distribution of structures with different contact form are calculated,and also starting time which is needed before temperature come into steady status.The result of analysis suggests that changing the contact form between inner heat shield and support cylinder can influence the thermal performance of cathode-heater assembly and improve assembly's temperature distribution and promote heater's heating efficiency.The result of this paper provides theoretical guidance in the design of cathode-heater assembly.

Phylogenetic diversity of eastern Asia-eastern North America disjunct plants is mainly associated with divergence time

The underlying causes of biodiversity disparities among geographic regions have long been a fundamental theme in ecology and evolution.However,the patterns of phylogenetic diversity(PD) and phylogenetic beta diversity(PBD) of congeners that are disjunctly distributed between eastern Asia-eastern North America(EA-ENA disjuncts) and their associated factors remain unknown.Here we investigated the standardized effect size of PD(SES-PD),PBD,and potentially associated factors in 11natural mixed forest sites(five in EA and six in ENA) where abundant EA-ENA disjuncts occur.We found that the disjuncts in ENA possessed higher SES-PD than those in EA at the continental scale(1.96vs-1.12),even though the number of disjunct species in ENA is much lower than in EA(128 vs 263).SESPD of the EA-ENA disjuncts tended to decrease with increasing latitude in 11 sites.The latitudinal diversity gradient of SES-PD was stronger in EA sites than in ENA sites.Based on the unweighted unique fraction metric(UniFrac) distance and the phylogenetic community dissimilarity,PBD showed that the two northern sites in EA were more similar to the six-site ENA group than to the remaining southern EA sites.Based on the standardized effect size of mean pairwise distances(SES-MPD),nine of eleven studied sites showed a neutral community structure(-1.96 ≤SES-MPD ≤1.96).Both Pearson’s r and structural equation modeling suggested that SES-PD of the EA-ENA disjuncts was mostly associated with mean divergence time.Moreover,SES-PD of the EA-ENA disjuncts was positively correlated with temperaturerelated climatic factors,although negatively correlated with mean diversification rate and community structure.By applying approaches from phylogenetics and community ecology,our work sheds light on historical patterns of the EA-ENA disjunction and paves the way for further research.

Research of Dynamic Material Handling in an Automobile General Assembly Line Based on Real-time Information

The status of material delivery of an automobile general assembly line is analyzed, and the technique to achieve the real-time tracking of assembly status information is proposed based on RFID（ Radio Frequency Identification）. Thus the consumption of line-side buffer is obtained dynamically, then the type and quantity of needed material are fed back to the subsystem of material handling; the algorithm for determining the best time departure time of delivery driver based on minimizing of total time penalty function is proposed. This approach makes the material amount of a single delivery trip maximized and improves the efficiency of delivery drivers significantly in the case of does not affect the assembly line normal throughput. Additionally, although this dynamic material handling method is developed for the automobile assembly plant, it should be pointed out that this method is also applicable to other mixed model assembly plants such as electronics, semiconductor and aerospace industry.

Supply Coordination Based on Bonus Policy in Assembly under Uncertain Delivery Time

The existing research of supply coordination under uncertain delivery time mainly focuses on the collaboration between the supplier and the manufacturer, which aim at minimizing the total cost of each side and finding comparative optimal solutions under decentralized decision. In the supply coordination, the collaboration between suppliers in assembly system is usually not considered. As a result, the manufacturer’s production is often delayed due to mismatching delivery of components between suppliers. Therefore, to ensure supply coordination in assembly system, collaboration between suppliers should be taken into consideration. In this paper, an assembly system with two suppliers and one manufacturer under uncertain delivery time is considered. The model is established and optimal solution is given under decentralized decision. Furthermore, the cost functions of two suppliers are both convex, and a unique Nash equilibrium exists between two suppliers. Then the optimal decision under supply coordination is analyzed, which is regarded as a benchmark for supply coordination. Additionally, the total cost of the assembly system is jointly convex in agreed delivery time. To achieve supply coordination a bonus policy is explored in the assembly system under uncertain delivery time, and the total cost under bonus policy must be lower than under decentralized decision. Finally the numerical and sensitivity analysis shows the cost of assembly system under bonus policy equals that under supply coordination, and the cost of each side in assembly system under bonus policy is lower compared to that under decentralized decision. The proposed research minimizes the total cost of each side with bonus policy in assembly system, ensures the supply coordination between suppliers and the manufacturer, and improves the competiveness of the whole supply chain.

Push-Pull Finite-Time Convergence Distributed Optimization Algorithm

With the widespread application of distributed systems, many problems need to be solved urgently. How to design distributed optimization strategies has become a research hotspot. This article focuses on the solution rate of the distributed convex optimization algorithm. Each agent in the network has its own convex cost function. We consider a gradient-based distributed method and use a push-pull gradient algorithm to minimize the total cost function. Inspired by the current multi-agent consensus cooperation protocol for distributed convex optimization algorithm, a distributed convex optimization algorithm with finite time convergence is proposed and studied. In the end, based on a fixed undirected distributed network topology, a fast convergent distributed cooperative learning method based on a linear parameterized neural network is proposed, which is different from the existing distributed convex optimization algorithms that can achieve exponential convergence. The algorithm can achieve finite-time convergence. The convergence of the algorithm can be guaranteed by the Lyapunov method. The corresponding simulation examples also show the effectiveness of the algorithm intuitively. Compared with other algorithms, this algorithm is competitive.

Application Research of assembly line modeling based on Time Petri Net

With the continuous progress of manufacturing industry,automatic assembly line has become a very mature production mode in modern factories,and the quality of assembly line design has become an important issue related to the development of manufacturing enterprises.In this paper,a graphical model based on Petri Net is established for the first full load time of the assembly line.The accessibility of the P/T system and the production rhythm of the assembly line are calculated by computer simulation.Finally,according to the simulation model,an experimental platform is built to verify the rationality of the model.Experimental results show that the model can accurately express the equipment allocation process of assembly line.

Assembling Tunable Time-Resolved Fluorescence Layer onto Nano-Gold

The assembling of a coating of time-resolved fluorescent chelator BSPDA （ abbreviated for 4, 7-bis （ sulfhydrylphenyl）-1, 10-phenanthroline-2, 9-dicarboxylic acid） onto a nano-gold layer was demonstrated. First, BSPDA was synthesized by simple procedures, and then an approach was developed to immobilize BSPDA onto the nano-gold layer deposited on a silane modified glass substrate, whereby europium ion （Ⅲ, Eu^3＋ ） was captured and released owing to the interactive process of complexation and dissociation between BSPDA functionalized coating and Eu^3＋ solution. The fluorescence spectra and related lifetimes were determined. Also, the BSPDA functionalized coating＇s specific complexation with Eu^3＋ on the BSPDA assembly layer and the nonspecific adsorption of Eu^3＋ on the nano-gold layer were compared. These results allowed a selective complexation of Eu^3＋ by assembling a BSPDA chelating layer on the nano-gold layer; thus, a tunable time-resolved fluorescent layer was covalently attached, The results of the nanoparticle assembling and probing （or labeling） processes to specific bio-systems were very interesting and had significant implications to time-resolved-fluorescence-based detection on biosensor surfaces such as DNA chip and to arrayed light display devices.

基于数字孪生的拖拉机混流装配智能排产仿真评价

车间排产对提高车间的效率至关重要,智能排产可以极大提高加工的自动化和智能化水平。但传统生产过程中大多采用固定的工时数据进行产线作业时间估算,而拖拉机混流装配以工人作业为主,工人作业时间不固定甚至存在较大差异。为满足智能排产要求,提出通过数字孪生车间对生产计划进行仿真评价以增强与实际车间的交互与反馈。搭建与现场拖拉机装配线一致的数字孪生三维模型场景及人机交互界面,根据MES系统中的过点信息实现装配线模型实时驱动,建立了一个拓展性强、可灵活复用的数字孪生系统。分析了生产计划评价指标,提出通过生产计划管理系统与孪生装配线的交互反馈,实现对基于数字孪生装配线的生产计划仿真运行及评价。通过数字孪生装配线采集到的实际工时仿真运行生产计划,可以得到优化后的生产计划。将低产、正常和高产月份各5 d内的实际生产计划与本系统生成的计划进行对比,结果表明本系统仿真评价后得到的生产计划更优越。

基于Matlab/Simulink的直线发动机性能仿真研究

建立了直线发动机的动力学及燃烧模型,通过Matlab/Simulink建模仿真,研究了直线发动机的运行特性,并定性分析了各主要设计、控制参数对系统性能的影响。研究结果表明:直线发动机的活塞组件质量直接影响系统输出性能,且在3.5~4 kg范围内输出功率较高;而对点火位置和喷油量的实时调节则是直线发动机控制的关键。

大规模定制环境下ATO供应链的混合补货策略

考虑按订单装配供应链由一个制造商和多个零部件供应商组成,按订单装配制造商对部分零部件采用准时制生产补货,其余零部件采用(Q,r)补货,建立了大规模定制环境下的按订单装配供应链零部件生产补货模型,研究了按订单装配制造商的混合补货策略和零部件供应商的生产策略,给出了制造商采用准时制生产补货方式的条件和供应链最优生产补货策略的寻优算法。理论和数值仿真分析表明,制造商应对采购价格较高、提前期较长或需求方差较大的零部件采用准时制生产补货方式,能够降低供应链库存成本,提高供应链利润。

发动机装配生产线ANDON系统的关键技术实现

结合我国发动机装配生产线自身特点,在建立装配生产线的数据采集与监控系统的基础上,开发了发动机装配生产线ANDON系统。该系统实现了现场设备与车间人员的实时信息交互,从现场级层面保证了发动机的装配质量,具有重要的理论与实际应用价值。

基于Petri网和改进遗传算法的多资源调度问题

针对混流装配线工序加工资源需求多样、工艺复杂、装配工期长等问题,采用Petri网和改进遗传算法对该问题进行优化求解。建立混流装配线赋时库所Petri网(timed place Petri net, TPPN)调度模型,基于模型激发序列,采用基于工序的编码方式进行染色体编码;采用精英保留策略选择优异个体,改进遗传算法的交叉、变异操作,用改进后的遗传算法求解混流装配线调度问题。通过对比案例及实例数据计算结果验证了方案的有效性。

单周期ATO系统的交货期与价格决策模型

交货期管理已经成为供应链管理研究的热点之一。针对价格和交货期相关需求下,含有两个组件的单周期ATO系统,首先考虑了由组件交货期不确定性对装配商带来的组件非一致性等待成本、组件提前交货的等待成本和产品延迟费用三种类型的提前期相关成本,然后建立了装配商的期望利润最大化的非线性规划模型,求出了最优的产品价格和承诺交货期,并对决策变量进行了敏感性分析,最后通过数值实验,研究了系统参数对装配商利润的影响。对订单装配企业交货期和价格决策具有一定的现实指导意义。

新型装配式软钢阻尼器梁柱节点的抗震性能及其时程分析研究

本文研究的是一种软钢阻尼器梁柱节点,并根据有无软钢阻尼器模拟的框架结构,在不同的地震波进行时程分析,为该节点的设计和建筑施工提供参考。利用ABAQUS有限元软件的数值模拟,对有无软钢阻尼器两种节点建模分析,从两种节点的滞回曲线、骨架曲线、耗能能力、刚度退化等抗震性能进行定量分析。结果表明有阻尼器的节点各力学性能均强于无阻尼器的节点,并且在有控情况下可以显著消耗建筑结构的地震能量,减小地震反应。因此本节点在有控情况下有利于装配结构在高烈度地区的推广使用,可以有效提高装配式结构的抗震性能,为装配式建筑施工在实际应用中提供参考。

电驱动总成多场耦合数据驱动建模及瞬态温度场实时在线预测

开发电驱动总成(EDA)轻量级实时在线温度精确预测方法,对于提前有效监测其未来异常温度状态,确保车辆行驶安全至关重要。基于多物理场耦合与数据驱动融合建模,提出了EDA瞬态温度场在线预测方法。首先,建立EDA电-磁-热-流多物理场耦合有限元模型,并通过台架试验验证该模型准确性;其次,采用有限元模型生成了几种常规工况下的瞬态温度场数据集,以用于后续代理模型的测试验证;然后,结合有限元模型获取简化的热网络拓扑和图卷积神经网络,提出一种模型与数据双轮驱动建模的EDA时空关系图卷积神经网络预测模型;最后,通过不同工况下的离线仿真对比分析和台架在线测试,对所提出的温度预测模型进行有效性和实时性验证。实测离线数据集上的分析结果表明:全局预测误差和平均绝对误差分别为4.4和1.25℃,相较于常规时序图卷积神经网络和门控递归单元方法分别降低17.3%、28.1%和5.3%、29.3%。台架在线预测结果也与真实测量值十分接近,其全局预测误差和平均绝对误差为3.99和0.66℃。总之,所提出的实时在线温度预测方法可以准确预测EDA真实温度变化。

基于微服务架构的智慧灯杆系统研究与应用

传统智慧灯杆系统实时数据的推送和获取需通过不断轮询,占用系统开销,网络带宽压力大,且高流量请求可能造成系统崩溃等问题。为解决上述问题,设计和实现了一种基于微服务架构的智慧灯杆数据实时推送系统。从业务实际需求出发,对系统技术架构与功能架构进行设计,明确4种技术模块与功能模块,并通过提取梳理模块、功能、实体以及资源结点的关系与属性,明确不同结点之间的权重,搭建图网络,采用图聚类算法将系统拆分为以实时数据推送服务为主的九大微服务。系统针对实时数据推送需求,采用双Redis数据库设计,分离实时数据与缓存数据,明确了3种实时数据存储结构以及数据点位表、转存配置表、系统三者之间的关系,启用Redis实时数据库键空间通知功能,监听特定键值变化,并通过Websocket实时推送到客户端。系统测试表明,该系统可以高效、准确地实现智慧灯杆实时数据推送以及历史数据的展示与存储,满足实时性与并发需求,其为智慧城市中的智慧灯杆数据可视化场景建设提供了完善的解决方案。

高层装配整体式剪力墙结构动力弹塑性时程分析

为了研究某高层建筑的抗震性能,对高层装配整体式剪力墙结构动力弹塑性时程进行分析。利用ABAQUS有限元软件,构建高层装配整体式剪力墙结构动力弹塑性材料本构关系有限元模型,模拟地震作用下高层装配整体式剪力墙结构动力时程变化情况。分析结果表明:整体剪力墙结构前6阶振型每两阶平动振型出现一个扭转,且计算结果符合规定,测试剪力墙时程位移变化结构也符合相关规定。随着地震波加载时间的增长,高层装配整体式剪力墙结构受拉损伤逐渐严重。加载至40s时,该结构的混凝土材料已经不能发挥作用,只能依靠钢筋支撑,但未出现明显坍塌,剪力墙结构受压损伤主要出现在剪力墙结构的连接位置,未出现明显受压损伤。说明该高层装配整体式剪力墙结构抗震性能良好。

R冷链企业混流生产线排产优化研究

以R冷链企业混流生产线为研究对象,以闲置时间与超载时间之和最小为目标建立排产优化模型。同时,考虑模型混流装配线投产的特性,采用遗传算法对模型求解。结果表明,混流生产线的投入产出比由75.5%提高至85.0%,日产量提高了11.26%,可以为冷链企业提高产能提供一定的参考。

采用混合连接装配式桥墩地震易损性分析

基于整体现浇桥墩试件(ZT-1)、现浇超高性能砂浆(UHPM)-CFST(钢管混凝土)榫卯混合连接桥墩试件(GX-1)、灌浆套筒-CFST榫卯混合连接桥墩试件(GT-1)的拟静力试验现象和结果,采用OpenSees有限元分析软件,开展试件在地震作用下的时程分析,并对其进行易损性评估,确定相对应的损伤量化指标,分析试件在地震作用下的易损性。研究结果表明:(1)在轻微破坏和中等破坏时,GT-1桥墩的易损性曲线变化趋势与ZT-1和GX-1桥墩较为接近;(2)当PGA分别为0.15 g、0.2g、0.3g、0.4g时,GX-1与ZT-1的地震反应均较为接近,与ZT-1桥墩试件相比,GT-1发生严重破坏的超越概率分别减小了6.71%、11.67%、10.32%、4.46%;(3)与ZT-1、GX-1相比,GT-1表现出更好的抗倒塌能力。

易代之际的遗民园林雅集与文学书写——以水绘园与稊园为中心

水绘园和稊园的设计都出于对现实中王朝兴替带来的痛苦的规避,但又各具特色,分别代表了明末清初与清末民初遗民园林的两种典型。易代之际的遗民园林雅集是“诗可以群”的文化传统与文人雅集的文化记忆之承续,“园隐”则是园林雅集文学书写的一大主题,是易代之际文人面临复杂的政治环境和生存困境后作出的安全选择。遗民园林对易代之际文化传承起到重要作用,象征着“精神桃源”。易代之际的遗民借助现实的文化空间,将非常态的人生境遇、改朝换代的沧桑之感揉进纵情逸乐的极致享受中,勾连起对往事的追忆与挽留,代表着一种重返故国、回归故园的人生渴望。园林的封闭性与自足性隔绝了永失故园的沉痛悲苦,代替故园成为一处超越现实的精神存在,存放鼎革之际的文化记忆,寄托着遗民们对现实世界与个人处境的迫厄之感与避世之愿。